/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package com.sun.org.apache.xml.internal.security.transforms.implementations;

import java.io.OutputStream;

import com.sun.org.apache.xml.internal.security.signature.NodeFilter;
import com.sun.org.apache.xml.internal.security.signature.XMLSignatureInput;
import com.sun.org.apache.xml.internal.security.transforms.Transform;
import com.sun.org.apache.xml.internal.security.transforms.TransformSpi;
import com.sun.org.apache.xml.internal.security.transforms.TransformationException;
import com.sun.org.apache.xml.internal.security.transforms.Transforms;
import com.sun.org.apache.xml.internal.security.utils.Constants;
import com.sun.org.apache.xml.internal.security.utils.XMLUtils;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

/**
 * Implements the <CODE>http://www.w3.org/2000/09/xmldsig#enveloped-signature</CODE>
 * transform.
 *
 * @author Christian Geuer-Pollmann
 */
public class TransformEnvelopedSignature extends TransformSpi {

  /**
   * Field implementedTransformURI
   */
  public static final String implementedTransformURI =
      Transforms.TRANSFORM_ENVELOPED_SIGNATURE;

  /**
   * Method engineGetURI
   *
   * @inheritDoc
   */
  protected String engineGetURI() {
    return implementedTransformURI;
  }

  /**
   * @inheritDoc
   */
  protected XMLSignatureInput enginePerformTransform(
      XMLSignatureInput input, OutputStream os, Transform transformObject
  ) throws TransformationException {
    /**
     * If the actual input is an octet stream, then the application MUST
     * convert the octet stream to an XPath node-set suitable for use by
     * Canonical XML with Comments. (A subsequent application of the
     * REQUIRED Canonical XML algorithm would strip away these comments.)
     *
     * ...
     *
     * The evaluation of this expression includes all of the document's nodes
     * (including comments) in the node-set representing the octet stream.
     */

    Node signatureElement = transformObject.getElement();

    signatureElement = searchSignatureElement(signatureElement);
    input.setExcludeNode(signatureElement);
    input.addNodeFilter(new EnvelopedNodeFilter(signatureElement));
    return input;
  }

  /**
   * @return the node that is the signature
   */
  private static Node searchSignatureElement(Node signatureElement)
      throws TransformationException {
    boolean found = false;

    while (true) {
      if (signatureElement == null
          || signatureElement.getNodeType() == Node.DOCUMENT_NODE) {
        break;
      }
      Element el = (Element) signatureElement;
      if (el.getNamespaceURI().equals(Constants.SignatureSpecNS)
          && el.getLocalName().equals(Constants._TAG_SIGNATURE)) {
        found = true;
        break;
      }

      signatureElement = signatureElement.getParentNode();
    }

    if (!found) {
      throw new TransformationException(
          "transform.envelopedSignatureTransformNotInSignatureElement");
    }
    return signatureElement;
  }

  static class EnvelopedNodeFilter implements NodeFilter {

    Node exclude;

    EnvelopedNodeFilter(Node n) {
      exclude = n;
    }

    public int isNodeIncludeDO(Node n, int level) {
      if (n == exclude) {
        return -1;
      }
      return 1;
    }

    /**
     * @see com.sun.org.apache.xml.internal.security.signature.NodeFilter#isNodeInclude(org.w3c.dom.Node)
     */
    public int isNodeInclude(Node n) {
      if (n == exclude || XMLUtils.isDescendantOrSelf(exclude, n)) {
        return -1;
      }
      return 1;
      //return !XMLUtils.isDescendantOrSelf(exclude,n);
    }
  }
}
